1. Field of the Invention
This invention relates generally to an improved electronic package, and more particularly, to an electronic package having improved thermal properties.
2. Background
In the electronics industry, the rapid development and extensive use of integrated circuits, such as silicon based semiconductor devices, have resulted in the proliferation of package designs to house the electronic devices. The packages take many forms including those which may be broadly categorized as hermetic or non-hermetic.
Hermetic packages are generally formed from ceramic or metal components and are usually glass sealed. Non-hermetic packages are generally formed from ceramic, metal or plastic components and are usually epoxy sealed. Non-hermetic packages are also formed by molding a plastic body around the electronic device. All such packages may be characterized by having an electronic component such as a silicon based semiconductor device mounted within the package and a leadframe having inner lead ends within the package and adapted for connection to the electronic device by wire bonds. The leadframe also includes outer lead ends extending out from the package for connection to an external device.
During the use of the electronic packages, heat is generated by the electronic component. This heat must be dissipated, as the build up of heat in the package may result in damage to the operability of the electronic system or even the failure of the overall system in which the package is used. Heat removal from the metallic packages occurs predominantly by heat flow through the seal epoxy, particularly the layer of epoxy attaching the leadframe to the base. Since the epoxy has relatively poor thermal conductivity, this limits the thermal performance of the package. In the plastic packages, even those with a heat slug or heat spreader, there exists a similar problem. The heat has to flow through poorly conducting epoxy at some point.